Inflator

ABSTRACT

The present invention provides an inflator which has a sufficient operation performance and secures an operation reliability and operation safety and is manufactured easily.  
     There is provided an inflator provided with a first passage for guiding activation energy of an igniter and a second passage for guiding a pressurized medium to a gas discharging port defined inside and outside two retainers having a cylindrical peripheral wall portion, in which the ruptureble plate sealing the pressurized medium space is held by two retainers disposed axially adjacent to each other.

TECHNICAL FIELD IN WHICH THE INVENTION BELONGS

[0001] The present invention relates to an inflator for inflating typesafety system of a vehicle, and in particular, to an inflator which cansecurely discharge a gas for inflating an air bag and does notcomplicate its structure, and in which a gas to be discharged is cleanwithout substantially containing a combustion residue.

BACKGROUND ART

[0002] With the development of an inflator for an inflating-type safetysystem of motor vehicles, a hybrid inflator using both a pressurized gasand a gas generating agent has been attracting attention, and thishybrid inflator inflates an air bag by opening a sealed state of thepressurized gas to discharge the pressurized gas.

[0003] Such an inflating-type safety system of vehicles is required toactivate securely as needed, and naturally, an inflator used therein isalso required to activate reliably.

[0004] In particular, in an inflator using a pressurized gas, it isnecessary to securely activate a mechanism for opening a sealed state ofthe pressurized gas charged in an interior of a housing in order toassure its operation reliability. In many cases, a rupturable plate isused as sealing means for a pressurized gas, and the sealed state isopened by rupturing the rupturable plate. Then, a pressure in apressurized gas accommodating chamber raised by a flame (or heat,hereinafter, used in the same manner) or a gas generated by combustionof a solid gas generating agent, breaking of a sealing member by aprojectile or the like, or an impact wave, a flame, a gas or the likegenerated at a time of activation of an igniter is ordinarily used forrupturing the rupturable plate. Among them, it is particularly desirableto use an impact wave, a flame, a gas or the like generated at a time ofactivation of an igniter for reducing weight of an inflator as a simpleconstitution, and there are conventionally various proposals.

[0005] For example, a technique in which an inlet for guiding acombustion product (an impact wave, a flame, a gas or the like)generated by activation of an igniter into the interior of a pressurizedmedium accommodating chamber and an outlet for guiding a pressurized gasin the pressurized medium accommodating chamber to a gas dischargingport are covered with a single rupturable plate and the rupturable plateis ruptured by activation of an igniter is disclosed in U.S. Pat. No.6,217,065. And the embodiment thereof describes a state in which arupturable plate is deformed to bulge towards the igniter by receiving apressure of the pressurized medium before activation. However, in theart disclosed in this document, only a peripheral portion of therupturable plate is fixed by welding, a welding radius becomesnecessarily large. As a result, there occurs such a case that, even ifthe igniter is activated, the rupturable plate is not ruptured but onlychanged its original shape (the shape bulging toward the igniter) to bebulged or deformed toward the opposite direction (to the opposite sideto the igniter), being divided based on the welded portion.

[0006] Further, U.S. Pat. No. 6,062,599 discloses the art in which aninlet and an outlet to a pressurized gas chamber are covered with asingle rupturable plate as in the case of U.S. Pat. No. 6,217,065 andcombinations of welding the rupturable plate at two portions and fixingthe same, and welding only a peripheral portion of the rupturable plateto form a fragile portion is included. Every art disclosed in thisdocument contributes to rupturing of the rupturable plate, but workingcost is increased since an extra welding step is required and it isnecessary to provide the fragile portion in the rupturable plate.

[0007] In the inflator using the pressurized gas, it is desirable todischarge a gas efficiently in order to inflate an air bag rapidly at atime of activation, and therefore it is important that an interiorstructure of a housing is designed to obtain an efficient gas flow inthe housing. Particularly, in a hybrid inflator using a flame or a gasgenerated by combustion of a solid gas generating agent, it is importantto obtain an effective gas flow in view of efficiently using a flame ora gas generated by combustion of the gas generator.

[0008] Further, since a gas generated by combustion of the gasgenerating agent at a time of activation of the hybrid inflator has ahigh temperature, desirably, the hybrid inflator is formed such that agas generated by combustion of the gas generating agent is notdischarged directly, for improving a safety at activation. Then, a solidcombustion product (combustion residue) generated by combustion of thegas generating agent has also a high temperature and there is a concernthat an air bag (a bag body) may be damaged when the gas is dischargeddirectly, and therefore, it is desirable that such a combustion residueis prevented from directly flowing out of the housing with a flow of anoperating gas for inflating an air bag. In other words, desirably, a gasto be discharged outside the housing is clean, including little residue.

[0009] Since an inflator having a complicated structure increases thenumber of manufacturing steps and a manufacturing cost, and an inflatorhaving an increased volume causes inconvenience due to a relationshipwith an arrangement space, it is necessary to avoid the complication ofthe inflator structure and the increase of the container.

[0010] However, with respect to the inflator for inflating type safetysystem of a vehicle which activates an air bag effectively, namely whichnot only inflates the air bag to a predetermined size in a predeterminedtime but also secures an operation reliability or an activation safetyif required, and that facilitates manufacturing, there is still a roomfor development.

DISCLOSURE OF THE INVENTION

[0011] An object of the present invention is to provide an inflator forinflating type safety system having a simple structure and realizingreduction in size and weight, in which, even though a simple structure,a rupturable plate can be securely ruptured in order to securelydischarge a gas for inflating an air bag and even when a gas generatingagent was used, a flame ora gas generatedby combustion of agasgenerating agent can further be utilized without discharging a residuegenerated by combustion thereof outside a housing, and, an air bagsystem using the same.

[0012] The present invention provides an inflator which can discharge agas for inflating an air bag efficiently, and can utilize a flame or agas generated by combustion thereof even when using a gas generatingagent, and wherein a flow path (“a first flow path” shown hereinafter)for guiding an activation energy of an igniter starting activation ofthe inflator and a flow path (“a second flow path” shown hereinafter)for guiding a gas for inflating an air bag are formed different toimprove a reliability of the inflator at activation, and a rupturableplate closing the first flow path and the second flow path is interposedbetween two retainers defining both the flow paths to be fixed easilyand securely so that an energy generated by activation of the ignitercan be transmitted to the rupturable plate efficiently.

[0013] That is, the inflator according to the present invention is aninflator for inflating type safety system of a vehicle, provided with apressurized medium space charged with a pressurized medium and anigniter chamber partitioned from the pressurized medium in an inflatorhousing having a gas discharging port, wherein a first passage forguiding an activation energy of an igniter and a second passage forguiding the pressurized medium to the gas discharging port are definedoutside and inside two retainers arranged adjacent to each other in theaxial direction and having a cylindrical peripheral wall portion, and arupturable plate for sealing the pressurized medium space is interposedbetween the two retainers adjacent to each other in the axial direction.

[0014] The inflator of the present invention is formed to rupture therupturable plate by an activation energy of the igniter, namely a flame,a gas or an impact wave generated by activation of the igniter, and tobe activated. By rupturing the rupturable plate due to the activationenergy of the igniter in this manner, an interior structure of theinflator can be made simpler and lighter in weight.

[0015] Then, the first passage for guiding an activation energy of theigniter is closed by a portion (hereinafter, referred to as a firstrupturable portion) of the rupturable plate existing in the firstpassage and a periphery of the first rupturable plate is held by tworetainers having a cylindrical peripheral wall portion, and therefore,when an activation energy of the igniter is received, the firstrupturable portion is prevented from deforming and bulging toward theopposite side to the igniter by the retainers, and when furtheractuation energy is received, the first rupturable portion is securelyruptured in the vicinity of inner peripheral edges of the retainersblocking bulging of the first rupturable portion. That is, by limitingdeforming or bulging of the entire rupturable plate toward thepressurized medium accommodating chamber with the retainers, the firstrupturable portion can be securely broken at activation of the igniter.

[0016] As described above, since the inflator according to the presentinvention is constituted such that deforming or bulging of therupturable plate is suppressed by the retainers at a time of actuationand the rupturable plate is ruptured by an activation energy of theigniter, even a rupturable plate which does not have a fragile portionsuch as a notch or the like can also be used as the rupturable plate. Byusing the rupturable plate which does not have a fragile portion such asnotch or the like, a manufacturing cost can be suppressed, which isdesirable.

[0017] Therefore, according to the present invention, an inflator inwhich the number of welded portions in the retainers can be reduced andthe retainers are ruptured securely by activation energy of the igniterwithout providing a fragile portion in the rupturable plate can berealized. In this case, in order to rupture the first rupturable portionmore securely, it is desirable that the igniter is provided oppositelyto the first rupturable portion and no obstacle exists between them.

[0018] The two retainers holding the above-described rupturable plateare formed to have cylindrical peripheral wall portions, and therupturable plate can be held between both the retainers by providing theretainers axially adjacent to each other. In this case, either oneretainer exists in the pressurized medium space defined by therupturable plate and the other retainer exists outside the pressurizedmedium space.

[0019] Further, desirably, the first passage and the second passage areprovided concentrically and both the passages are defined by theretainers provided with cylindrical peripheral wall portions. Byarranging the passages in this manner, a compact inflator can berealized and further the first passage and the second passage can beclosed by a single member (the rupturable plate), and thus manufacturingcan be made easier. If the rupturable plate is formed integrally suchthat a second rupturable portion exists to surround a periphery of thefirst rupturable portion, the rupturable plate can be manufacturedeasily, and consequently reduction in manufacturing cost can beachieved.

[0020] By defining the first passage and the second passage by theretainers, the first passage is provided inside the retainers and thesecond passage is provided outside the same. Both the passages aredefined by the two retainers without air ventilation therebetween.Thereby, even when the igniter is activated, almost all activationenergy thereof acts for rupturing the rupturable plate without flowinginto the second passage and gases in the first and second passagesduring inflator actuation do not interfere with each other, so that aninflator actuated securely can be obtained.

[0021] The two retainers adjacent to each other in the axial directioncan be realized as a first retainer existing outside the pressurizedmedium accommodating chamber and a second retainer existing inside thepressurized medium accommodating chamber. In this case, the rupturableplate can be held between the first retainer and the second retainer.

[0022] If the first retainer is disposed such that a distal end portionof the igniter is surrounded circumferentially by an axial one endportion thereof and the other end thereof contacts the rupturable plate,all activation energy generated by activation of the igniter is led tothe rupturable plate to securely rupture the rupturable plate, which isdesirable.

[0023] It is desirable that the first retainer which guides activationenergy of the igniter is formed to have an inclining portion in whichthe inner diameter is getting smaller toward the rupturable plate. Byforming the retainer in this manner, activation energy of the ignitercan be concentrated to rupture more securely the rupturable plate.

[0024] Further, by providing an end portion closing member constitutinga portion of the inflator housing at an axial end portion of thehousing, defining an igniter chamber inside the end portion closingmember, and forming gas discharging ports penetrating radially the endportion closing member, assembling of the inflator can be facilitated.In this case, it is preferable that a peripheral edge portion of therupturable plate is fixed to the end portion closing member by weldingor the like.

[0025] The inflator of the present invention is preferably a hybridinflator in which one or two combustion chambers for accommodating a gasgenerating agent are provided inside the housing. The combustion chambercan be provided either inside or outside the pressurized medium space,but desirably, the combustion chamber is provided in the pressurizedmedium space in order to effectively utilize a combustion gas or heatgenerated by combustion of the gas generating agent. When the combustionchamber is provided inside the pressurized medium space, the firstpassage can be provided between the igniter chamber and the combustionchamber.

[0026] In the hybrid inflator, when the igniter is activated, activationenergy thereof ruptures a portion (the first rupturable portion) of therupturable plate existing in the first passage to reach the inside ofthe pressurized medium space and ignites and burns the gas generatingagent in the combustion chamber existing in the space.

[0027] In this series of operations, since the rupturable plate is heldby the two retainers in the inflator of the present invention, when thefirst rupturable plate is ruptured to be absent between the retainers nolonger, a clearance corresponding to the thickness of the rupturableplate (a communicating space) is formed at the place (i.e., an abutmentportion of the retainers). When such a clearance is generated, acombustion gas and a combustion residue of the gas generating agentflows out into the second passage through the clearance (hereinafter,referred to as “short-pass”).

[0028] In view of the above, in the hybrid inflator according to thepresent invention, it is desirable to provide a passage closing memberwhich is moved by a pressure in the pressurized medium space atactuation to close the communicating space of the first passage and thesecond passage, obtained between the retainers after the rupturableplate is ruptured. Thereby, a combustion gas and a combustion residueare prevented from short-passing to the second passage from theclearance formed between the retainers. Particularly in the hybridinflator, since the interior of the housing is temporarily under a highpressure by combustion of the gas generating agent, an effect obtainedby closing the first passage by the passage closing member due to thepressure and preventing communication between the passages at theclearance between the retainers is effective.

[0029] In order to close the communicating space between the firstpassage and the second passage after the rupturable plate is ruptured,desirably, the first passage in the combustion chamber side is closedrather than the communicating space. For this reason, it is desirablethat the passage closing member is formed to have a size, a shape and amass such as to be moved by a pressure inside the pressurized mediumspace activated at actuation of the inflator and to be capable ofclosing at least the first passage. As such a passage closing member,for example, a metal ball, an substantially conical metal member or thelike can be used, and it is especially desirable that a shape of themember is a ball, because it can close the first passage securelyregardless of the orientation of the member after moved.

[0030] The passage closing member is disposed inside the pressurizedmedium accommodating space, and more desirably in the rupturable plateside in the combustion chamber. By disposing the member in this manner,the passage closing member receives a pressure of a combustion gasgenerated by combustion of the gas generating agent or a pressure insidethe pressurized medium space increased by the combustion gas and ismoved in the direction to the clearance formed between the retainers toclose the same.

[0031] In particular, if the gas discharging port and the clearanceformed between the retainers are close to each other, the combustionresidue passing through the clearance is discharged directly from thegas discharging port to the outside of the housing, and therefore, it isessential to close the clearance by the passage closing member.

[0032] In order to close the first passage by the passage closingmember, for example, among two retainers forming the first passage, in aretainer (the second retainer) existing inside the pressurized mediumaccommodating chamber before activation in the rupturable plate side, abent portion for forming an opening smaller than an inner diameter ofthe cylindrical peripheral wall portion thereof may be provided, and thebent portion and the passage closing member may be pressed against eachother. Thereby, the combustion gas generated inside the combustionchamber is sealed between the bent portion and the passage closingmember so that it is prevented from short-pass from the clearancebetween the retainers toward the second passage.

[0033] As a result, all the gas for inflating an air bag, including thecombustion gas of the gas generating agent, is discharged from the gasdischarging ports through the second passage. Thus, a hybrid inflator inwhich a combustion gas is not discharged directly can be provided.Further, as all the operating gas passes through the second passage, thecombustion product (hereinafter, referred to as a combustion residue)except the gas generated by combustion of the gas generating agentstrikes against an inner wall of the housing or the like and is removedfrom the operating gas at the time of being discharged from thecombustion chamber to pass through the second passage, so that apossibility that the combustion residue discharged from the gasdischarging ports can be suppressed as much as possible.

[0034] In particular, in order to make the combustion residue generatedby combustion of the gas generating agent remain in the housing moreeffectively, it is desirable to provide many flow direction changingpoints of operating gas flow. For example, when a through hole fordischarging combustion gas from the combustion chamber is formed on aperipheral surface of the cylindrical container defining the combustionchamber, it is desirable that the through hole is formed in a directionperpendicular to the inner surface of the housing or at least two flowdirection changing portions for changing a direction of a gas flow isprovided in a passage of the combustion gas from the combustion chamberto the gas discharging port.

[0035] Further, in order to ignite the gas generating agent moresecurely, it is desirable that a transfer charge ignited and burnt bythe activation energy of the igniter is disposed at any position in thecombustion chamber. In this case, in order to improve an ignition of thetransfer charge ignited by the igniter, it is desirable that no obstacleto movement of the activation energy of the igniter, such as a passageclosing member exists between the rupturable plate and the transfercharge.

[0036] In the inflator of the present invention constituted as describedabove, since all the gases flowing inside the housing flows in onedirection and a flow of one gas is not disturbed by the flow of anothergas, the gas flows in the housing are not disturbed and flow in onedirection. As a result, the gas for inflating an air bag can bedischarged efficiently.

[0037] And when the inflator of the preset invention is a hybridinflator, by providing the first passage and the second passageseparately, a combustion flame or a combustion gas of the gas generatingagent can be utilized further effectively and a flame or hot gasgenerated by combustion of the gas generating agent is not directlydischarged, so that activation safety also becomes further preferable.In particular, since the first passage for guiding activation energy ofthe igniter is provided inside two retainers axially adjacent to eachother and it is extended to the interior of the pressurized medium spaceby the two retainers (particularly by the second retainer), theactivation energy of the igniter is guided even in the pressurizedmedium space. As a result, it is convenient to ignite the gas generatingagent disposed inside the pressurized medium space. That is, such afeatures of the present invention that the rupturable plate is held bytwo retainers and either one of the retainers exists in the pressurizedmedium space is especially suitable for the hybrid inflator, because theactivation energy of the igniter can be guided into the combustionchamber in the pressurized medium space.

[0038] As the pressurized medium which can be used in the presentinvention, a conventionally known material can be used, and one having acomposition which comprises an inert gas such as argon, helium or thelike (nitrogen is also included in the inert gas in the presentinvention) and that does not include oxygen substantially can be used.In this case, the argon works to promote the thermal expansion of thepressurized medium. It is preferable to contain helium in thepressurized medium since the leakage of the pressurized medium can bedetected easily, and consequently distribution of imperfect products canbe prevented. A charging pressure of the pressurized medium ispreferably 10,000 to 70,000 kPa and more preferably, 30,000 to 60,000kPa.

[0039] Further, as the gas generating agent used when the inflator ofthe present invention is the hybrid inflator, a conventionally known gasgenerating agent can be used. Incidentally, in order to remove thecombustion residue (the combustion product other than a gas) moreeffectively, it is desirable to use a gas generating agent whichgenerates a combustion product having a melting point higher than thedischarging temperature of the gas generated by combustion of the gasgenerating agent. By relating the discharging temperature of the gasgenerated from the gas generating agent and the melting point of thecombustion residue contained in the combustion gas to each other, thegeneration of a massive (slag-like) combustion residue can be promoted.By making a gas including the slag-like combustion residue strikeagainst an inner surface of the housing or the like, the combustionresidue can be removed from the gas. In particular, when the secondpassage is provided to surround the first passage and the second passageis formed to allow a gas to pass, the combustion residue included in thegas strikes against a wall surface of the second passage to becollected, which is desirable.

[0040] The discharged gas temperature of the gas generating agent can beobtained from an tank internal pressure (actually measured value), anamount of generated gas, and a specific heat of the generated gasgenerally when the gas generating agent is burnt inside a tank having apredetermined volume. When the melting point of the residue becomessufficiently higher than the discharged gas temperature (not less than110° C., preferably not less than 500° C.), the combustion residue iseasily solidified and agglomerated (slag-like), so that it remains inthe inflator and is suppressed from being discharged out of theinflator.

[0041] As the gas generating agent which can be used in the presentinvention, for example, it is possible to use one including fuel and anoxidizing agent, or fuel, an oxidizing agent and a slag-forming agent,being mixed with a binder if required, and formed into a desired shape.If such a gas generating agent is used, a gas generated by combustion ofthe agent can be used for inflating and developing the air bag togetherwith the pressurized medium. Particularly when the gas generating agentincluding the slag-forming agent is used, since it becomes easier toform a slag, an amount of mist-like combustion residue discharged fromthe inflator can be largely reduced. However, when an amount of the gasgenerating agent to be charged is small and an amount of the residue tobe generated is small, the slag-forming agent may not be used in view ofa gas generating efficiency.

[0042] Preferably, the fuel can be one or two or more selected from thegroup constituting guanidine derivatives such as nitroguanidine (NQ),guanidine nitrite (GN), guanidine carbonate, amino nitro guanidine,amino guanidine nitrate, amino guanidine carbonate, diamino guanidinenitrate, diamino guanidine carbonate, and triamino guanidine nitrite.Furhter, as fuel, one or two or more selected from the group consistingof tetrazole and tetrzole derivatives can be used.

[0043] Preferably, the oxidizing agent can be one or two or moreselected from the group consisting of strontium nitrate, potassiumnitrate, ammonium nitrate, potassium perchrolate, copper oxide, ferrousoxide, a basic copper nitrate.

[0044] Preferably, the slag-forming agent can be one or two or moreselected from the group consisting of acid clay, talc, bentonite,diatomaceous earth, kaolin, silica, alumina, sodium silicate, siliconnitride, silicon carbide, hydrotalsite, and a mixture thereof.

[0045] Preferably, the binding agent can be one or two or more selectedfrom the group consisting of sodium salt of carboxymethylcellulose,hydroxyethyl cellulose, starch, polyvinyl alcohol, guar gum,microcrystal cellulose, polyacrylamide and calcium stearate.

[0046] When the pressurized medium and the gas generating agent havingthe above-described compositions are used, it is preferable that a molarratio (A/B) between an amount (A mol) of the pressurized medium and anamount (B mol) of gas generated due to combustion of the gas generatingagent is adjusted to 0.2 to 10, and more preferably 0.4 to 4.

[0047] As described above, the charging amount of the pressurized mediumcan be reduced by adjusting the molar ratio between an amount ofpressurized medium and an amount of a gas generated by combustion of thegas generating agent. Therefore, even when a volume of the inflatorhousing is reduced by making the pressurized medium space smaller (i.e.,even when the length and/or width (diameter) of the housing is reduced),it is possible to maintain the pressure at the same level as that beforethe volume is reduced, without increasing the charging pressure(=internal pressure of the pressurized medium) of the pressurizedmedium. In the present invention, when the inflator is a hybridinflator, a weight ratio (X/Y) of a weight (X) of the pressurized mediumto a weight (Y) of the gas generating agent is preferably 0.1 to 7, andmore preferably 0.5 to 5.

[0048] The present invention provides an inflator for inflating typesafety system with a simple structure in which a gas for inflating anair bag can be securely discharged and, even when a solid gas generatingagent burnt to generate a gas is used, a flame or a gas generated bycombustion of a gas generating agent can further be efficiently usedwithout discharging a residue produced by combustion thereof to theoutside of the housing, and that realizes reduction in size and weightwith a simple structure, and also provides an air bag system using thesame.

BRIEF DESCRIPTION OF THE DRAWINGS

[0049]FIG. 1 is an axial sectional view showing an embodiment of ahybrid inflator.

[0050]FIG. 2 is an axial sectional view showing a state of the hybridinflator in FIG. 1 after activation starts.

[0051]FIG. 3 is a sectional view of a principal portion showing anactivation starting state of the hybrid inflator.

[0052]FIG. 4 is a sectional view of the principal portion showing anactivation starting state of the hybrid inflator. and

[0053]FIG. 5 is a sectional view of the principal portion showing anactivation starting state of the hybrid inflator.

DESCRIPTION OF NUMERALS

[0054]1 inflator housing

[0055]2 pressurized medium space

[0056]3 combustion chamber

[0057]4 gas generating agent

[0058]5 igniter

[0059]9 first retainer

[0060]10 second retainer

[0061]12 rupturable plate

[0062]13 first rupturable portion

[0063]14 second rupturable portion

[0064]15 first passage

[0065]16 second passage

[0066]17 communicating space

[0067]18 metal ball

[0068]19 bent portion

PREFERRED EMBODIMENTS OF THE INVENTION

[0069] An embodiment of the present invention will be explained belowwith reference to the drawings.

[0070]FIG. 1 is an axial section showing a preferred embodiment of aninflator according to the present invention, and FIG. 2 is an axialsection showing a state of the inflator after activation starts.

[0071] An inflator according to the present embodiment is an aspect of ahybrid inflator utilizing heat or a gas generated by combustion of asolid gas generating agent 4 at a time of activation, and an example ofa dual type (a multi-stage type) hybrid inflator provided with twoigniters 5 activated independently is shown.

[0072] In the hybrid inflator, a pressurized medium space 2 charged witha pressurized medium is provided in a cylindrical inflator housing 1, acombustion chamber 3 accommodating a gas generating agent 4 is providedinside the pressurized medium space 2, and igniters 5, 5′ are arrangedat both axial end portions of the inflator housing 1.

[0073] The inflator housing 1 comprises a cylindrical member 6, whichhas a strength to withstand increase in pressure generated inside thepressure chamber (namely, the pressurized medium space 2), and two endportion closing members 7, 7′ for closing end openings thereof, andigniter chambers 8, 8′ for accommodating the igniters 5, 5′ are providedinside the respective end portion closing members 7, 7′. Between two endportion closing members 7, 7′, the end portion closing member 7(hereinafter, referred to as a first end portion closing member 7) whichis positioned in the side (namely, on the left side of the drawing)where retainers 9, 10 described later are provided is provided with gasdischarging ports 11 radially penetrating through the first end portionclosing member 7.

[0074] The pressurized medium space 2 provided inside the inflatorhousing 1 is charged with an inert gas such as argon, helium or the liketo serve as a pressure chamber, and the pressure chamber is closed by arupturable plate 12 existing at an end surface of the first end portionclosing member 7 in the pressurized medium space 2 side to be maintainedin an air tight state. A partition wall 30 provided to axially dividethe pressurized medium space into two is disposed inside the pressurizedmedium space 2. The partition wall 30 is provided with plural throughholes for communicating the divided spaces with each other.

[0075] A cylindrical container 23 provided on its peripheral surfacewith plural through holes 22 is disposed inside the pressurized mediumspace 2, and it is charged with the gas generating agent 4 to be thecombustion chamber 3. A flame, heat, combustion gas and the likegenerated by combustion of the gas generating agent 4 are dischargedfrom the through holes 22 of the cylindrical container 23 to inflate thepressurized medium. As the gas generating agent 4, a conventionallyknown material can be used, but, specially preferably, a material whichdoes not produce a product (liquid type, solid type, semi-solid type orthe like) other than the gas at activation, or a material whichgenerates a combustion product (combustion residue) removed by making anoperating gas strike against an inner surface of the housing 1 issuitably used. Especially, the cylindrical container 23 provided withthe through holes 22 is arranged to face an inner surface of thecylindrical member 6 constituting the housing 1, and the through holes22 are formed perpendicularly to the inner surface of the cylindricalmember 6, and thereby, the combustion residue discharged from thethrough holes 22 collides against the inner surface of the cylindricalmember 6 to be removed. Further, in this embodiment, the gas, which haschanged its flow direction after striking against the inner surface ofthe housing 1, strikes against the first end portion closing member 7this time to change its flow direction. That is, the inner surface ofthe cylindrical member 6 and the first end closing member 7 constitutingthe housing 1 serve as the direction changing portions, and thecombustion residue included in the gas is removed by the change of theflow direction.

[0076] Two retainers 9, 10 are provided to be connected from the igniter(hereinafter, referred to as a first igniter 5) provided in the firstend portion closing member 7 toward the inside of the housing 1. The tworetainers 9, 10 are both provided with cylindrical peripheral wallportions and a rupturable plate 12, which hermetically closes thepressurized medium space 2, is interposed between the retainers 9, 10adjacent to each other in the axial direction. In this embodiment, theretainer existing outside the pressurized medium space 2, namely,existing nearer to the igniter 5 than the rupturable plate 12 is definedas a first retainer 9 and the retainer existing inside the pressurizedmedium is defined as a second retainer 10.

[0077] A first passage 15 for guiding actuation energy (a flame, a gas,an impact wave and the like) of the igniter 5 is secured inside thefirst retainer 9 and the second retainer 10, and, in the outsidethereof, a second passage 16 for guiding an operating gas for inflatingan air bag is defined by the retainers and the inner peripheral wall ofthe first end portion closing member 7. That is, the first passage 15and the second passage 16 are defined by the two retainers 9, 10.

[0078] In this embodiment, particularly, the first retainer 9 forguiding the activation energy of the igniter 5 to the rupturable plate12 is formed as an inclining portion in which the inner diameter of itsperipheral wall (a cylindrical peripheral wall portion) formedcylindrically is getting smaller from the igniter 5 toward therupturable plate 12. Thereby, the activation energy of the igniter 5 canbe concentrated to more securely rupture the rupturable plate 12. Theinclining portion may be provided only in the vicinity of a portioncontacting with the rupturable plate in the first retainer 9.

[0079] As the rupturable plate 12 sealing the pressurized medium space2, one metal plate formed in a circular shape is used, and the firstpassage 15 and the second passage 16 are closed by the one metal plate(the rupturable plate 12). Then, since the rupturable plate 12 formed inone plate piece is held between the two retainers 9, 10, it is preventedfrom bulging (deforming) toward the pressurized medium space at the timeof receiving the actuation energy of the igniter 5, even if it is notwelded at a periphery of the first passage 15. And, if a break as anotch is not formed, the rupturable plate 12 can securely be ruptured ata time of activation of the igniter 5. In order to prevent expansion ofthe rupturable plate 12 at the time of receiving the actuation energy ofthe igniter 5 and to rupture the rupturable plate securely, it isdesirable that the inner diameter (an inner diameter of the firstpassage 15) of a portion contacting the rupturable plate 12 in thesecond retainer is approximately equal to the inner diameter (the innerdiameter of the first passage 15) of a portion contacting the rupturableplate 12 in the first retainer, however, the inner diameter of a portioncontacting the rupturable plate in the second retainer can be larger bythe thickness of the portion contacting the rupturable plate in thefirst retainer, as shown in FIG. 3.

[0080] At this time, as shown in FIG. 3, the rupturable plate 12 isdeformed to be pressed against the first retainer 9, receiving apressure of the pressurized medium. In this state, when the igniter isactivated, an activation energy thereof overcomes the pressure of thepressurized medium, so that the first rupturable portion 13 of therupturable plate 12 deforms to bulge toward the combustion chamber 3side (namely, toward the pressurized medium space side) as shown in FIG.4. At this time, the rupturable plate 12 comes in contact with an edgeportion 28 of the second retainer 10 so that the edge portion 28 acts toprevent deformation of the entire rupturable plate 12. Furthermore, whenenergy from the igniter is applied to the first rupturable portion 13,the first rupturable plate 13 is sheared at the edge portion 28 to becut off. At this time, the first rupturable portion 13 is cut off almostas a whole, as shown in FIG. 5. In this case, a shape of a portion to becut off may be jaggedly cut off mainly at the portion corresponding tothe edge portion 28 in the rupturable plate.

[0081] A rupturable plate portion (a second rupturable portion 14) whichreceives a pressure of the pressurized medium and exits inside thesecond passage 16 is also ruptured due to the influence of the ruptureof the first rupturable portion 13. Thereby, a communicating space 17such as shown in FIG. 2 may occur at butting portions of the retainers9, 10 holding the rupturable plate 12.

[0082] In view of the above, in the inflator shown in this embodiment,as shown in FIG. 2, a passage closing member (a metal ball 18) whichmoves due to a pressure inside the pressurized medium space 2 atactivation to close the communicating space 17 between the first passage15 and the second passage 16 after rupture of the rupturable plate 12 isdisposed. The metal ball 18 is provided in the rupturable plate 12 sideinside the combustion chamber 3 before activation of the inflator, asshown in FIG. 1, and it receives a pressure at a time of combustion ofthe gas generating agent 4 or a pressure of the activated pressurizedmedium and moves in the direction to close the communicating space 17after activation of the inflator, as shown in FIG. 2.

[0083] A bent portion 19 which tightly contact the moved metal ball 18to close the first passage 15 is provided nearer to the pressurizedmedium space 2 than the communicating space 17 in the first passage 15(specifically, inside the second retainer 10), and a short-pass of theoperating gas or the combustion residue from the first passage 15 to thesecond passage 16 is prevented by pressing the bent portion 19 and themetal ball 18 against each other. Incidentally, a chain line shows aflow of a gas in FIG. 2.

[0084] A transfer charge 20 which is ignited and burnt by activationenergy of the igniter 5 is disposed inside the first passage 15 and themetal ball 18 is pressed and supported together with the transfer charge20 by and a supporting member 21 defining the combustion chamber 3. Arecess for receiving part of the metal ball 18 is formed in thesupporting member 21, and the metal ball 18 is received in the recessand is prevented from moving before activation. The metal ball 18 is notin contact with the second retainer 10 to be directly supported by thesecond retainer 10, and a clearance 27 is provided between the metalball 18 and the second retainer 10. The clearance 27 serves to lead aflame of the transfer charge 20 to the combustion chamber 3.Incidentally, in order to lead the flame of the transfer charge 20 intothe combustion chamber 3, plural through holes 26 are formed in thesupporting member 21 or the supporting member 21 is formed by using awire mesh.

[0085] An operation of the inflator according to this embodiment will bedescribed. When the igniter 5 is activated upon receipt of an activationsignal, activation energy is generated and it reaches the firstrupturable portion 13 through the inside of the first retainer 9 (thefirst passage 15) thereby rupturing the same. At this time, the secondrupturable portion 14 also receives a pressure of the pressurized mediumand is ruptured, so that the pressurized medium space 2 is put incommunication with the outside of the housing 1 via the second passage16 and the gas discharging ports 11. Almost simultaneously with ruptureof the second rupturable portion 14, the activation energy of theigniter 5 ignites the transfer charge 20 inside the second retainer 10and a flame thereof passes inside the second retainer 10 (the firstpassage 15) to ignite and burn the gas generating agent 4 inside thecombustion chamber 3. The pressure inside the pressurized medium space 2increases due to combustion of the gas generating agent 4 and,simultaneously therewith, the metal ball 18 receives a combustion gas ofthe gas generating agent 4 or a pressure of the pressurized medium tomove in the direction in which the rupturable plate 12 existed andclosely contact the bent portion 19 of the second retainer 10 to closethe first passage 15. Thereby, outflow of the combustion gas, thecombustion residue and the pressurized medium from the communicatingspace 17, which is formed between the retainers 9, 10, to the secondpassage 16 is blocked. As a result, all the combustion gas generated inthe combustion chamber 3 and the pressurized medium (operating gas)passes through the second passage 16 to be discharged from the gasdischarging ports 11. Since the flow-direction changing portion (theinner surface of the cylindrical member 6 and the first end portionclosing member 7) for changing a flow direction of a gas is provided inthe passage of the operating gas inside the housing 1, the combustionresidue contained in the gas is removed so that a clean gas isdischarged. Further, since all of the combustion gas passes through theinterior of the pressurized medium space 2, heat or the combustion gasdue to combustion of the gas generating agent 4 can effectively beutilized.

[0086] In the inflator housing 1, the igniter 5′ fixed to the endportion closing member 7′ provided oppositely to the first end portionclosing member 7 is activated properly if required, and when activated,the igniter 5′ is activated simultaneously with the first igniter 5 orwith a slight delay.

[0087] Incidentally, in the present embodiment, the inflator with twoigniters 5, 5′ is described, however the inflator according to thepresent invention can further employ a structure having only a left halfportion in FIG. 1, namely, a single type structure constituted with onlya left half portion (in the side in which the combustion chamber exists)divided from the partition wall 30 provided inside the cylindricalportion of the housing. In this case, the inflator can be formed to havea structure which is closed by a member with no hole for closing an endportion, instead of the partition wall 30. Furthermore, even in astructure without using the generating agent 4, it is possible torupture the first rupturable portion 13 and the second rupturableportion 14 by a gas, heat, an impact wave or the like generated byactivation of an igniter by the structure in which the first retainer 9and the second retainer 10 hold the both sides of the ruptrable plate.In this case, since no residue occurs, a metal ball is not required.

[0088] An air bag system of the present invention can be manufactured byincorporating the above-described hybrid inflator. That is, it is an airbag system provided with activation-signal outputting means comprisingan impact sensor and a control unit, and a module including a modulecase accommodating a hybrid inflator and an air bag. The hybrid inflatoris connected to the activation-signal outputting means (the impactsensor and the control unit) at the igniters 5, 5′ existing at both endsof the housing 1 and the inflator is connected and fixed in the modulecase mounted with an air bag by screwing a stud bolt. Then, in the airbag system having such a structure, it is possible to adjust an amountof gas generation and an inflating speed of the air bag according to themagnitude of an impact by properly setting activation signal outputtingconditions in the activation-signal outputting means.

[0089] The hybrid inflator of the present invention can be applied tovarious inflators such as an inflator for an air bag for a driver side,an inflator for an air bag for a passenger side next to the driver, aninflator for a side air bag, an inflator for a curtain air bag, or thelike.

1. An inflator for inflating type safety system for a vehicle, providedwith, in an inflator housing having a gas discharging port, apressurized medium space charged with a pressurized medium and anigniter chamber partitioned from the pressurized medium, wherein a firstpassage for guiding an activation energy of an igniter and a secondpassage for guiding the pressurized medium to the gas discharging portare defined in the outside and the inside of two retainers having acylindrical peripheral wall portion arranged axially adjacent to eachother, and a rupturable plate for sealing the pressurized medium spaceis held between the two retainers axially adjacent to each other.
 2. Aninflator according to claim 1, wherein the first passage is definedinside the second passage, and the first passage and the second passageare closed by an integrated single rupturable plate.
 3. An inflatoraccording to claim 1 or 2, wherein the rupturable plate comprises afirst rupturable portion closing the first passage and a secondrupturable portion closing the second passage, and the igniteraccommodated in the igniter chamber is positioned oppositely to thefirst rupturable portion.
 4. An inflator according to claim 3, whereinthe first rupturable portion receives the activation energy of theigniter directly to be ruptured.
 5. An inflator according to any one ofclaims 1 to 4, wherein the rupturable plate is constituted such thatdeforming or budging of the entire rupturable plate toward thepressurized medium accommodating chamber due to the activation energy ofthe igniter is limited by the retainers.
 6. An inflator according to anyone of claims 1 to 5, wherein the two retainers axially adjacent to eachother are a first retainer existing outside the pressurized mediumaccommodating chamber and a second retainer existing inside thepressurized medium accommodating chamber, and the rupturable plate isheld between the first retainer and the second retainer.
 7. An inflatoraccording to claim 6, wherein the first retainer circumferentiallysurrounds a distal end portion of the igniter by its axial one endportion, and makes the other portion contact with the ruputurable plateto be arranged in a housing.
 8. An inflator according to any one ofclaims 1 to 7, wherein an end portion closing member constituting aportion of the housing is provided at an axial one end portion of theinflator housing, and the igniter chamber is defined and provided insidethe end portion closing member, and gas discharging ports radiallypenetrating the end portion closing member are formed in the end portionclosing member.
 9. An inflator according to claim 8, wherein therupturable plate is fixed at its peripheral portion to the end portionclosing member.
 10. An inflator according to any one of claims 1 to 9,wherein a combustion chamber accommodating a gas generating agentignited and burnt by the activation energy of the igniter, and a passageclosing member which moves due to a pressure inside the pressurizedmedium space at activation to close a communicating space between thefirst passage and the second passage after the rupturable plate isruptured are provided inside the inflator housing.
 11. An inflatoraccording to claim 10, wherein the combustion chamber is provided insidethe pressurized medium accommodating space, the first passage isprovided between the igniter and the combustion chamber, and the passageclosing member is provided between the rupturable plate and thecombustion chamber.
 12. An inflator according to claim 10 or 11, whereinthe combustion chamber is provided inside a cylindrical containerdisposed inside the pressurized medium space, and plural through holesdirecting perpendicularly to an inner surface of the housing are formedon a peripheral surface of the cylindrical container.
 13. An inflatoraccording to claim 12, wherein all combustion gas generated inside thecombustion chamber is discharged from the through holes to reach the gasdischarging port.
 14. An inflator according to any one of claims 10 to13, wherein at least two flow direction changing portions for changing aflow direction of a gas are provided in a passage of the combustion gasgenerated in the combustion chamber from the combustion chamber to thegas discharging port.
 15. An inflator according to any one of claims 10to 14, wherein the second rupturable plate is ruptured by at least oneof a pressurized medium pressure and combustion gas pressure of the gasgenerating agent.
 16. An inflator according to any one of claims 10 to15, wherein a bent portion forming an opening smaller than an innerdiameter of a cylindrical peripheral portion is provided at an endportion in the rupturable plate side of a retainer (a second retainer),among the two retainers, existing inside the pressurized mediumaccommodating chamber and the bent portion is formed in a shape to bepressed by the passage closing member and close the communicating space.17. An inflator according to any one of claims 10 to 16, wherein atransfer charge ignited and burnt by activation energy of the igniter isdisposed inside an cylindrical peripheral wall of a retainer (a secondretainer), among the two retainers, existing inside the pressurizedaccommodating chamber, and the transfer charge is pressed and supportedby a supporting member defining the combustion chamber together with thepassage closing member.
 18. An inflator according to any one of claims10 to 17, wherein the passage closing member is a metal ball, the metalball is disposed in the combustion chamber side inside a retainer (asecond retainer), among the two retainers, existing in the pressurizedmedium accommodating chamber, and an inner diameter of a portion of thesecond retainer in the vicinity of the passage closing member is formedto be larger than an outer diameter of the metal ball at least beforeactivation of the inflator.
 19. An inflator according to any one ofclaims 1 to 18, wherein, among the two retainers, a retainer (a firstretainer) exiting outside the pressurized medium accommodating chamberhas an inclining portion which is gradually reduced in diameter towardan end portion thereof in the rupturable plate side.
 20. An air bagsystem comprising activation-signal outputting means including an impactsensor and a control unit, and a module case accommodating an inflatoraccording to any one of claims 1 to 19 and an air bag.